What lurks in the darkness
by kathaka9
Summary: What is making Sherlock so confused? Who is this mysterious man who has all the answers? What lurks in the darkness?
1. Chapter 1

**Can you come down to Scotland Yard? -GL**

**What's the case? -SH**

**Just come down, i'll explain everything. -GL**

**Be there soon. -SH**

"John we've got a case. Lestrade wants us to go down to Scotland Yard." John nodded and went up to his room to grab a jacket. Sherlock grabbed his coat and scarf. John came back down the stairs. Together they walked onto the street and Sherlock hailed a cab.

The cab drive was tedious, the driver kept yelling at cars in front of him. John was relieved when they could finally get out of the cab. Sherlock paid the cabbie and walked off towards Scotland Yard, followed by John. They walked into Lestrade's office and sat down.

"What is it this time?" John asked.

"We found 5 people dead at 22 Oswin St..."

Sherlock interrupted him: "There's something different, you wouldn't call me unless there's something interesting."

"I was getting to that. When we found them, they were just bones. Not even a single bit of skin left."

John was horrified that someone would do that to a person. Sherlock, however, was intrigued. "Lestrade, I need to see the scene."

Sherlock smiled and walked off to go and catch a cab. John had to run to catch up to him. Why did he always have to do this? Sherlock had stopped to hail a cab. His ability to be able to hail cabs anywhere made John jealous. Why couldn't he do that? They got into the cab and went to 22 Oswin St.

When they arrived at the scene Sherlock pulled out a magnifying glass and began examining the scene. Anderson groaned when he saw Sherlock, "Why are you here, freak?"

"To solve the case." If Anderson had said anything else Sherlock hadn't listened or cared.

After about an hour Sherlock still hadn't found anything useful. He decided that there wasn't anything useful at the scene so he took a sample of each of the bones to examine. He went back to flat so he could examine them. When they were back at the flat Sherlock sat in front of his microscope for hours examining the bones.

Something was each one of the bones, but he had no idea what it was. It was something he had never come across before. What was this substance? What could it possibly be? For the first time in his life Sherlock didn't know something.

When John came down to check on Sherlock, Sherlock was on his phone researching something. "You need to sleep Sherlock!"

Sherlock grunted and said "No, i'm fine. Sleep slows me down."

"But we don't want you collapsing at a crime scene... again."

"I'll be fine."

John gave in and went upstairs to get some sleep.

For a whole week Sherlock didn't eat or sleep. He hardly ever left his microscope. John was getting very worried. Is it time to get some help?

Sherlock's head shot up and he said "I don't need help, John." He was doing it again, reading peoples minds. How does he do it?

The next day John's phone went off.

**I've been texting Sherlock for days, he won't answer. Are you two okay? -GL**

**I'm fine. Not so sure about Sherlock though. -JW**

**What's he done this time? -GL**

**He hasn't been eating or sleeping all week. -JW**

**Can you get Sherlock to come down to the Yard. -GL**

**I'll try. -JW**

"Sherlock, Greg wants you to come down to the Yard." Sherlock looked up from his experiment at John. "Greg?"

"Lestrade. Have you deleted his name again?"

"It's not important enough for me to remember."

"Are you coming or not?"

"Fine, I'll come."

They took a cab down to Scotland Yard. During the cab ride Sherlock was unusually quiet. John tried to make conversation but was ignored. When they finally got to the Yard John was relieved, he paid the cabbie and they walked to Lestrade's office. Lestrade greeted them at the door. "Hello. It's the same as before."

"Where?"

"At 72 Bond St."

Sherlock went outside and caught a cab to 72 Bond St.

John caught a ride with Lestrade. When they got there Sherlock was examining things and muttering to himself. There still wasn't anything useful. Suddenly Sherlock saw someone in the distance. Someone familiar. Who was he again? Before anyone could stop him Sherlock ran off in the direction of this mysterious person.

John spotted Sherlock running and went after him. When he caught up Sherlock was talking to a man who was wearing possibly the most ridiculous clothes he's ever seen. Sherlock looked annoyed as the man explained something John could not understand.


	2. Chapter 2

"Do you understand why you cannot chase them around London?"

"Yes. You already explained." Sherlock replied in a monotone.

"So you see why you shouldn't even try and chase them?"

"Well it'd be illogical, you can't chase a shadow. Even if you did how would you know you if it was the right shadow?"

"You can't... until you see it in action."

"EXACTLY!"

John was not following any of this. "Sherlock? Who is this and what on earth are you talking about?"

Sherlock pondered for a bit then said "This is the Doctor. We were..."

"Doctor who?"

The Doctor laughed "Exactly."

Sherlock sighed but continued anyway... "We were talking about what is committing those murders."

"Wait did you say what? Don't you mean who?"

"No it's what."

"What is it?"

Sherlock looked at the doctor prompting him to say it. "Well technically what we're dealing with are Vashta Nerada, but you probably have no idea what that is. They're the piranhas of the air. They live in the shadows. You won't even know they're there until it's too late."

"So how are you supposed to catch them?"

The Doctor and Sherlock both looked uneasy. The John realised "You can't catch them."

"Yep, they're impossible to stop."

John felt very very uneasy "So, what do we do then?"

"Count the shadows, and run."

Sherlock shook his head. "We will be able to stop them. Everything has a weakness."

The Doctor glanced at Sherlock and said sadly "Everything but the Vashta Nerada,"

"No. We can stop them, and we will."

"How?"

Sherlock went very silent all of a sudden. He looked genuinely confused. The Doctor sighed and said "Look, I'm pretty sure it's just a small group of them. It's not like they're going to be able to kill everyone. Maybe we can just leave it."

"No. We can't just leave it. Look, if you think we can leave let's go to the future and find out."

"Fine."

The three of them went to the TARDIS. As John stepped in he gasped. "It's bigger on the inside!" The Doctor and Sherlock laughed. Why did nobody bother to think? Of course it's bigger on the inside. How else would they all fit?

The Doctor started up the TARDIS. They were sent rocketing about through time and space.

When they landed Sherlock stepped out of the TARDIS first. The others promptly followed. They were horrified by what they saw. The earth was in ruins, skeletons littered the streets. It looked like no one had been alive for centuries.

"How far into the future are we?"

"Only 5 months." The doctor replied grimly.

"There must be some way to stop this! Can't we change the future? I mean I know its probably like a fixed point in time or will cause a paradox. Why do I even know that? I need to do some deleting! Anyway we can't let the earth end up like this! There won't be any murder cases left for me to solve!"

John rolled his eyes. "Really? I mean, REALLY? Isn't this one big HUGE murder case?"

The doctor looked over at Sherlock and grabbed him excitedly. "Sherlock Holmes you're a genius! If we somehow stop the Vashta Nerada in the past then none of this will have ever happen! Now the question is... How do we stop them?

* * *

**A/N: Hey guys sorry I haven't updated in a while. Does any one have any ideas on how to kill Vashta Nerada (other than light)? Please I'm super stuck! **


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